Zoology XII+ - Human Reproduction 11

Question : 1

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Fertilization is a physio-chemical process that can occur only if sperm and ovum are transported simultaneously at a particular region. Which is considered to be the best site for this event so that chances of its survival are more?

Options:

	Beginning of fallopian tube
	Junction of ampulla and isthmus
	Body cavity where oocyte is released from ovary
	Junction of infundibulum and ampulla

Solution :

(2)

 

If fertilization occurs at the site other than junction of ampulla and isthmus, the chances of ectopic pregnancy is high, which is generally terminated before full

term.

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Question : 2

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Human male ejaculate about 2–3 ml of semen into vagina of female during coitus. Which of the following must be required for normal fertility?

Options:

	At least 60% sperms must be of normal shape and size
	At least 40% of them must show vigorous motility
	The sperm count should be at least 50 million/ejaculation
	Both (1) & (2)

Solution :

(4)

 

For normal fertility sperm count should be at least 200-300 million / ejaculation.

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Question : 3

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Fertilization is species specific and this specificity is provided by fertilizin-antifertilizin reaction. Antifertilizin is produced by

Options:

	Mature eggs
	Immature eggs
	Capacitated sperms
	Decapacitated sperms

Solution :

(3)

 

Mature/capacitated sperms produce antifertilizin and mature eggs produce fertilizin.

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Question : 4

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Fertilizin is basically a

Options:

	Glycoprotein
	Acidic protein
	Steroid
	Phosphoprotein

Solution :

(1)

 

Fertilizin is produced by mature ovum and is a glycoprotein.

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Question : 5

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In the absence of which ion, fertilization does not occur even if approximation between male and female gamete has taken place?

Options:

	K+
	Ca+2
	Na+
	Cl−

Solution :

(2)

 

Ca⁺² is responsible for changing undulating movement of sperms to whiplash movement.

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Question : 6

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Fertilization includes the following different events in humans. Find the exact sequence of events happening

a. Cortical reaction

b. Recognition

c. Agglutination

d. Reception cone formation

e. Depolarisation

f. Acrosomal reaction

g. Zona reaction

Options:

	b − c − f − d − e − a − g
	b − c − d − f − e − a − g
	c − b − f − d − g − e − a
	c − b − d − f − a − g − e

Solution :

(1)

 

In case of humans only that sperm is able to fertilize ovum which show recognition and agglutination.

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Question : 7

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Which of the following event occurs immediately after the entry of first sperm into ovum?

Options:

	Influx of Na+
	Acrosomal reaction
	Formation of fertilization membrane
	Oocyte completes its meiosis II immediately

Solution :

(1)

 

After entry of 1^st sperm, depolarization wave spreads.

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Question : 8

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Which of the following will be included under slow blockage to polyspermy?

Options:

	Depolarisation of egg membrane
	Cortical reaction
	Zona reaction
	Both (2) & (3)

Solution :

(4)

 

Depolarisation is the fast blockage whereas cortical reaction and zona reaction are slow blockage to polyspermy

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Question : 9

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During the course of fertilization, which of the following layers A, B & C will be degraded by hyaluronidase?

 

Options:

	A
	B
	C
	Both A & C

Solution :

(1)

 

A – Corona radiata

B – Zona pellucida

C – Perivitelline space.

 

Hyaluronidase dissolve hyaluronic acid, a cementing substance between follicles of corona radiata.

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Question : 10

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Depolarisation of egg membrane results in release of Ca²⁺ ions from endoplasmic reticulum. This Ca²⁺ wave causes

Options:

	Release of fertilin from sperms
	Extrusion of cortical granules
	Dissolving of corona radiata
	Destruction of receptors for sperms on zona pellucida

Solution :

(2)

 

Ca²⁺ wave brings cortical granules to the surface that releases enzymes in pervitelline space that makes zona pellucida impervious to second sperm.